PHP Velho Oeste 2024

mysqli_result::fetch_field

mysqli_fetch_field

(PHP 5, PHP 7, PHP 8)

mysqli_result::fetch_field -- mysqli_fetch_fieldRetorna o próximo campo no conjunto de resultados

Descrição

Estilo orientado a objetos

public mysqli_result::fetch_field(): object|false

Estilo procedural

mysqli_fetch_field(mysqli_result $result): object|false

Retorna a definição de uma coluna de um conjunto de resultados como um objeto. Utilize esta função repetidamente para obter informação sobre todas as colunas no conjunto de resultados.

Parâmetros

result

Somente no estilo procedural: Um objeto mysqli_result retornado por mysqli_query(), mysqli_store_result(), mysqli_use_result() ou mysqli_stmt_get_result().

Valor Retornado

Retorna um objeto que contém informações sobre a definição do campo ou false se nenhuma informação de campos estiver disponível.

Propriedades do objeto
Propriedade Descrição
name O nome da coluna
orgname Nome original da coluna se foi especificado um apelido
table O nome da tabela à qual este campo pertence (se não calculada)
orgtable Nome da tabela original se foi especificado um apelido
def Reservado para o valor padrão, atualmente sempre igual a ""
db O nome do banco de dados
catalog O nome do catálogo, sempre igual a "def"
max_length O tamanho máximo do campo para o conjunto de resultados.
length A largura do campo, como especificada na definição da tabela.
charsetnr O número do conjunto de caracteres para o campo.
flags Um inteiro representando os bits de opções para o campo.
type O tipo de dados usado para este campo
decimals O número de decimais usadas (para campos inteiros)

Exemplos

Exemplo #1 Estilo orientado a objetos

<?php
$mysqli
= new mysqli("localhost", "my_user", "my_password", "world");

/* verifica a conexão */
if (mysqli_connect_errno()) {
printf("Conexão falhou: %s\n", mysqli_connect_error());
exit();
}

$query = "SELECT Name, SurfaceArea from Country ORDER BY Code LIMIT 5";

if (
$result = $mysqli->query($query)) {

/* Obtém informação do campo para todos os campos */
while ($finfo = $result->fetch_field()) {

printf("Name: %s\n", $finfo->name);
printf("Table: %s\n", $finfo->table);
printf("max. Len: %d\n", $finfo->max_length);
printf("Flags: %d\n", $finfo->flags);
printf("Type: %d\n\n", $finfo->type);
}
$result->close();
}

/* fecha a conexão */
$mysqli->close();
?>

Exemplo #2 Estilo procedural

<?php
$link
= mysqli_connect("localhost", "my_user", "my_password", "world");

/* verifica a conexão */
if (mysqli_connect_errno()) {
printf("Conexão falhou: %s\n", mysqli_connect_error());
exit();
}

$query = "SELECT Name, SurfaceArea from Country ORDER BY Code LIMIT 5";

if (
$result = mysqli_query($link, $query)) {

/* Obtém informação do campo para todos os campos */
while ($finfo = mysqli_fetch_field($result)) {

printf("Name: %s\n", $finfo->name);
printf("Table: %s\n", $finfo->table);
printf("max. Len: %d\n", $finfo->max_length);
printf("Flags: %d\n", $finfo->flags);
printf("Type: %d\n\n", $finfo->type);
}
mysqli_free_result($result);
}

/* fecha a conexão */
mysqli_close($link);
?>

Os exemplos acima produzirão:

Name:     Name
Table:    Country
max. Len: 11
Flags:    1
Type:     254

Name:     SurfaceArea
Table:    Country
max. Len: 10
Flags:    32769
Type:     4

Veja Também

add a note

User Contributed Notes 8 notes

up
61
iansoko at hotmail dot com
12 years ago
here are the data types that correspond to the TYPE number returned by fetch_field.

thought i would post this here since i couldn't find the info elsewhere.

numerics
-------------
BIT: 16
TINYINT: 1
BOOL: 1
SMALLINT: 2
MEDIUMINT: 9
INTEGER: 3
BIGINT: 8
SERIAL: 8
FLOAT: 4
DOUBLE: 5
DECIMAL: 246
NUMERIC: 246
FIXED: 246

dates
------------
DATE: 10
DATETIME: 12
TIMESTAMP: 7
TIME: 11
YEAR: 13

strings & binary
------------
CHAR: 254
VARCHAR: 253
ENUM: 254
SET: 254
BINARY: 254
VARBINARY: 253
TINYBLOB: 252
BLOB: 252
MEDIUMBLOB: 252
TINYTEXT: 252
TEXT: 252
MEDIUMTEXT: 252
LONGTEXT: 252
up
3
Anonymous
12 years ago
The constants for the TYPE number returned by fetch_field are enumerated here (MYSQLI_TYPE_*):
http://php.net/manual/en/mysqli.constants.php
up
13
ragtag at hotmail dot com
15 years ago
The flags used by MySql are:
NOT_NULL_FLAG = 1
PRI_KEY_FLAG = 2
UNIQUE_KEY_FLAG = 4
BLOB_FLAG = 16
UNSIGNED_FLAG = 32
ZEROFILL_FLAG = 64
BINARY_FLAG = 128
ENUM_FLAG = 256
AUTO_INCREMENT_FLAG = 512
TIMESTAMP_FLAG = 1024
SET_FLAG = 2048
NUM_FLAG = 32768
PART_KEY_FLAG = 16384
GROUP_FLAG = 32768
UNIQUE_FLAG = 65536

To test if a flag is set you can use & like so:
<?php
$meta
= $mysqli_result_object->fetch_field();
if (
$meta->flags & 4) {
echo
'Unique key flag is set';
}
?>
up
2
andre at koethur dot de
9 years ago
Here are two methods for converting the 'type' and 'flags' attributes to text for debugging purposes. They both use the predefined MYSQLI_ constants to generate the text.

<?php

public static function h_type2txt($type_id)
{
static
$types;

if (!isset(
$types))
{
$types = array();
$constants = get_defined_constants(true);
foreach (
$constants['mysqli'] as $c => $n) if (preg_match('/^MYSQLI_TYPE_(.*)/', $c, $m)) $types[$n] = $m[1];
}

return
array_key_exists($type_id, $types)? $types[$type_id] : NULL;
}

public static function
h_flags2txt($flags_num)
{
static
$flags;

if (!isset(
$flags))
{
$flags = array();
$constants = get_defined_constants(true);
foreach (
$constants['mysqli'] as $c => $n) if (preg_match('/MYSQLI_(.*)_FLAG$/', $c, $m)) if (!array_key_exists($n, $flags)) $flags[$n] = $m[1];
}

$result = array();
foreach (
$flags as $n => $t) if ($flags_num & $n) $result[] = $t;
return
implode(' ', $result);
}

?>
up
1
sofe2038 at gmail dot com
5 years ago
The constants in a few other comments above appear to be inaccurate. Here are some more official references that seem quite hard to search.

The "type" attribute: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-type
The "flags" attribute: https://github.com/google/mysql/blob/master/include/mysql_com.h#L133

In addition, all attributes are explained on the COM_QUERY_RESPONSE page too: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition
up
1
rvila at revolutionvisualarts dot com
7 years ago
The predefined constant values returned by the function get_predefined_constants() for:

MYSQLI_TYPE_CHAR = 1
MYSQLI _TYPE_TINYINT = 1

If the code is used to categorized the type of field use this values will of course create confusion. For example:

if($fieldtype === "CHAR"){
$field_html_attribute = "text";
$field_html_length = 1;
} elseif($fieldtype === "TINYINT") {
$field_html_attribute = "number";
$field_html_length = 1;
}

If an array is created to set the key as the numeric value and the value of that key as the the text title, TINYINT will be replaced by CHAR value. But is this process is reversed, then the code will select TINYINT if the foreach statement set to break when the numeric value of the flag equals the value of the current key as the first intance.

Base in the note added by Johnathan at http://php.net/manual/en/mysqli.field-count.php the values should be:

CHAR = 254
TINYINT = 1

But predefined function attributes the value 254 to MYSQLI_TYPE_STRING.

Just for FYI
up
0
nick
6 years ago
It is not possible to get the values for an enum or set field through fetch_fields(). As far as I can tell this is because it hasn't been implemented in the mysqlnd api but whatever the reason it is not possible and you must issue a query like SHOW COLUMNS directly and interrogate the result to determine them.

Incidentally you need to check the enum_flag rather than look for the enum_type to determine whether a field is enum or not. The type returned is usually some kind of string.
up
2
miqrogroove at gmail dot com
11 years ago
Beware the values of the predefined constants. They do not always correlate with the actual field types. For example:

MYSQLI_TYPE_BLOB: 252
MYSQLI_TYPE_TINY_BLOB: 249
MYSQLI_TYPE_MEDIUM_BLOB: 250
MYSQLI_TYPE_LONG_BLOB: 251

MySQLi will indeed return a value of 252 for a tinytext field, but as you can see, this does not correspond to the value of MYSQLI_TYPE_TINY_BLOB.
To Top